Detrusor underactivity (DU) is a common but poorly understood clinical problem. The diagnosis and treatment of DU are very difficult and full of uncertainties. There are many overlaps between DU and bladder outlet obstruction (BOO). Patients with DU might have bladder function recovery after bladder outlet surgery. However, there was little report on the recovery of voiding efficiency (VE) after bladder outlet surgery in patients with detrusor acontractile (DA). Therefore, we aim to identify the predictive factors of recovery after prostate surgery in male patients with DA.

We retrospectively reviewed the male patients diagnosed as DA and received transurethral prostate surgery in Hualien Tzu Chi hospital over the past two decades. Urodynamic studies were performed before and after the operation. The urodynamic parameters including VE, maximum flow rate (Qmax) and post-void residual (PVR) volume were recorded for outcome evaluation. We defined bladder function recovery as having a VE > 50% after the bladder outlet surgery. Univariate and multivariate logistic regression analyses were performed to determine the predictors of patients with satisfactory therapeutic outcomes.

There were 48 male patients who had been diagnosed as DA and received transurethral prostate surgery in the past two decades. The average age was 74.4 ±10.0 years. The mean follow-up period was 24.9 ± 30.5 (1~108) months. At the most recent follow up, 29 (60.4%) patients match the criteria of VE recovery, whereas the other 19 (39.6%) did not reach a successful outcome. Among these patients, 21 (72.4%) of them were recovered within one month; only one of them was recovered after more than 6 months. After surgery, the patients’ Qmax, voided volume, PVR and VE all showed improvement in each group (Table 1). Especially in the recovery group, all the postoperative parameters showed significantly improved compared to the baseline (p=0.000). In the non-recovery group, only the PVR and VE had significant improvement. In comparison with the baseline urodynamic parameters between the two groups, we found that patients with a baseline higher detrusor pressure (Pdet), greater voided volume and higher Qmax recovered better (Table 2). We found no differences in age and the other parameters that reflected the bladder storage function. The pre-operative PVR showed no significant difference too. In logistic regression analysis, only Pdet and Qmax seem to be a predictor of successful outcome.

This study reveals that male patients with DA could regain bladder function and a better VE after transurethral prostate surgery. Patients with a higher Pdet, greater voided volume and higher Qmax at baseline seem to recover better. However, logistic regression revealed that significant difference was only found in Pdet and Qmax. The small case number seems to affect the statistical results. Conversely, the bladder sensation does not seem to affect the voiding function recovery. The main reason might point to the old age and underlying chronic disease, which masks the difference between the two groups. The baseline PVR was also not different between groups. It is due to the small case number and all DA patients presented to the clinic with urine retention or large PVR which was unrelated to their bladder contractility.

Sixty percent of male patients with urodynamic DA and urinary retention can have voiding function recovery after transurethral surgery. Although not all patients can have bladder function recovery after operation, some still can void spontaneously by abdominal straining. Prostate surgery reduces the bladder outlet resistance and provides an easier voiding by the aid of increased abdominal pressure. A higher baseline Pdet, voided volume and Qmax are predictive of successful treatment outcome after transurethral prostate surgery. The detrusor function might not be completely lost and has a better chance to regain efficient detrusor contractility after relief of BOO.